Blue leafer

n.

Heard in Dublin

A blue leafer is someone who knowingly spreads the transmission of a STD(STI) to another person, originates from the blue leaf disease of the Oak tree.

In use

See yer man over there? sure isnt he only a blue leafer!

Posh English

Observe the fellow over there, is he not a dreadful degenerate who knowingly disseminates maladies.